Investigation of the effectiveness of optical color measurement for screening UOC samples in nuclear forensics analysis

木村 祥紀; Shollenberger, Q. R.*; 松本 哲也*; Lindvall, R.*; Hoffman, D. C.*; 山口 知輝

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Uranium ores and uranium ore concentrates (UOCs) serve as front-end materials in the nuclear fuel cycle and exhibit distinct material characteristics, known as nuclear forensic signatures, which can assist in determining their origins such as the provenance and deposits. The interpretation of these signatures is often challenging due to the diversity of mining techniques and the complex nature of natural minerals. As part of a joint research collaboration between the Japan Atomic Energy Agency (JAEA) and the Nuclear Smuggling Detection and Deterrence (NSDD) program of NNSA/US DOE, we investigated nuclear forensic signatures and methodologies for tracing the origins of uranium-bearing materials, including ores and UOCs. This study focuses on the optical color measurement of UOCs as a potential screening method for identifying their chemical compounds. UOCs are known to exhibit a variety of colors, influenced by the oxidation states of uranium compounds and the presence of trace elements. Optical colors of seven UOC samples provided by JAEA were analyzed using different approaches by LLNL and JAEA. We will discuss the relationship between the optical colors of UOCs and their major uranium compounds as well as trace elements. The findings highlight the potential of optical color measurements as a screening tool to support nuclear forensic analysis and provide insights into the chemical diversity of UOCs.